Tongs with adjustable-friction joint



June 7, 1960 K. PUTSCH ETAL 2,939,215

TONGS WITH ADJUSTABLE-FRICTION JOINT Filed Sept. 15, 1959 2 Sheets-Sheet l TONGS WITH ADJUSTABLE-FRICTION JOINT Karl Putsch, Wuppertal-Hahncrberg, and Heinz Schmeisser, Wuppertal-Cronenberg, Germany, assignors to Firma C. Gustav Putsch, Wuppertal-Cronenberg, Germany, a corporation of Germany Filed Sept. 15, 1959, Ser. No. 849,030

Claims priority, application Germany Nov. 27, 1958 1 Claim. (Cl. 30-266) The present invention relates to adjustable tongs, to be used as a hand tool, for instance hammer tongs or bending pliers, the arms of which are connected by means of a working bolt.

In order to bring about an easily operating and playfree mounting of the arms of a shears-like tool, it is known to provide the so-called working bolt with a thread and to arrange the bolt in such a manner that the mounting friction of the engaging faces of the arms may be adjusted by a threading movement. This arrangement leads, however, to complicated and multi-part structures, since the adjusting screw must be safely arranged relative to the operational movements of the arms of the tool.

In particular in connection with tongs, a play-free, easy operation is desired in such a manner that oil containing lubricating cushions are provided between the engaging faces of the arms. In this connection, a bolt having a ball-shaped head which is threadedly adjustable in one of the arms of the tongs has been provided.

All known structures of the pivotal connection have the drawback, however, that the guiding effect is exerted merely in axial direction of the pivotal pin. Since the loosening of the connection is also dependent upon the wear of the radially carrying face of the bolt, the known structures do not lead to a play-free guide.

In the manufacture of tongs or the like, it is a known experience that in spite of observation of exact measurements for the respective co-operating parts, a more or less frictional movement between the arms of the tongs results even in the individual members of the same series, which movement depends upon circumstances of the assembly.

The operation of the tongs is, therefore, sometimes diflicult and undesirable. If this occurs, an appreciable disadvantage is apparent. If in particular engaging cutting edges are ground flat, the parallel arrangement of which determines the easy cutting step, and if a more or less great play is experienced in the pivot of the tongs, the required operational force for cutting a wire or the like becomes appreciably larger than usual, leading to a fast exhaustion of the hand muscles of the operator of the tongs.

In the industry, for instance in the radio and electrical industry, it is known that an appreciably large number of working places exist in which wire ends are shortened or wires are cut by means of tongs for many hours. For such working places, an easy manipulation of the tongs bringing about an easy and smooth cutting is of greatest essence.

It is, however, impossible to comply with this requirement, because the after-working of the tongs is, due to their structure, complicated and expensive and even then the changes brought about by the wear during operation cannot be removed anymore to obtain a play-free operation.

It is, therefore, one object of the present invention to provide adjustable tongs which in a simple and easily performing manner by the user himself is adjustable at any time to a great exactness as to its play-free operation.

' hired States Patent It is another object of the present invention to provide adjustable tongs having a working bolt and in which the working bolt has a truncated cone section which projects through one arm of the tongs rotatably and which'projects with its cylindrical section into the other arm of the tongs non-rotatably. The novel and essential features of the present invention resides in the fact that the truncated cone section of the working bolt is slotted to form legs and has a central funnel-shaped recess which receives the conically shaped head of a set screw, the shank of which isreceived in a threaded bore of the cylindrical section of the working bolt.

By this arrangement it is made possible that while the exact adjustment of the arms of the tongs is maintained, the play of the pivot of the tongs is adjustable by turning the working bolt to such an extent that the tongs operate easily, which means that the tongs close automatically at the border of free play.

By screwing in the set screw, the truncated cone section of the working bolt may be spread apart, whereby the latter engages more closely the bore in the arm of the tongs without changing the centering thereof.

A removal of the working bolt is possible, if desirable, by removal of the set screw, whereby the truncated cone claws return resiliently to their original position.

An undesirable removal of the set screw is thus prevented.

With these and other objects in view, which will become apparent in the following detailed description, the present invention will be clearly understood in connection with the accompanying drawings, in which:

Figure 1 is a side elevation of cutting tongs designed in accordance with the present invention;

Fig. 2 is a front elevation of the working bolt shown at an enlarged scale;

Fig. 3 is a section of the arm of the tongs co-ordinated to the working bolt shown in Fig. 2;

Fig. 4 is a top plan view of a working bolt set into the corresponding arm of the tongs; and

Fig. 5 is a section along the lines 55 of Fig. 4.

Referring now to the drawings, the tongs designed in accordance with the present invention comprise crossing arms 1, 2 the head ends of which carry the claws 3 and 4 which engage each other with their chisel-like edges. The arms 1 and 2 of the tongs engage each other at widened and flattened sections 1' and 2' and are rotatably or tumably connected by means of a working bolt 5.

The section 5 of the working bolt which projects through the arm 2 of the tongs is conically shaped, and in particular in such a manner that it is tapered outwardly towards its free end. The arm 2 of the tongs has a complementary coincally shaped bore 10 (Fig. 5).

The cylindrical section 5" of the working bolt may have an outer thread 6 and the arm 1 of the tongs co-operating therewith may have a complementary inner thread 7 which has on the outside of the pivot a counterbored widened seat 8, so that the bolt may be riveted in to be non-rotatable The truncated cone section 5' of the working bolt is preferably equipped with crosswise disposed slots 9 so that legs are formed which are radially resilient. The truncated cone section 5 of the working bolt has furthermore a funnel-shaped recess 11 which receives the conical- 1y shaped head 12 of a set screw, the shank 13 of which is received in a threaded bore 14 of the other section 5" of the working bolt.

If the two arms 1 and 2 of the tongs engage each other at the faces 1' and 2 and if the working bolt 5 is inserted as shown in Fig. 5 and non-rotatably riveted into the arm 1 of the tongs, the legs of the truncated cone section 5' of the working bolt may be more or less spread apart upon operation of the set screw. While an exact centering Patented. June. 7, 1960 position is then maintained, a greater or smaller play of the working bolt is made possible so that the friction of the pivot may be selectively adjusted.

vThe described structure is applicable not only for cutting tongs, but also for bending tongs or the like to a great advantage, where likewise an exact-parallel guide of the legs of the tongs is requiredfor an easy working operation.

While we have disclosed one embodiment of the present invention, it is to be understood that this embodiment is given by example only and not in a limiting sense, the scope of the present invention being determined by the objects and the claim.

We claim: a

Adjustable tongs having a pair of crossed arms with mutual engaging faces, a pivoting Working bolt projecting through said arms for a pivotal connection of the latter, said working bolt having a truncated cone section rotatably received in one of said arms and a cylindrical section. non-rotatably secured in' the other of said arms, said.

truncated cone section having radial slots dividing said section, whereby adjustment of said set screw with respect I to said working bolt affects the pressure of said legs against said one arm, thereby changing the frictional resistance between said arms.

References Cited in the file of this patent UNITED STATES PATENTS 624,175 Chapman May 2, 1899 2,582,184 Wheeler Jan. 8, 1952 2,596,767 Erickson May 13, 1952 2,704,399 Melcher -Mar. 22, 1955 FOREIGN PATENTS 550,626 Great Britain Jan. 18, 1943 

